-
Notifications
You must be signed in to change notification settings - Fork 0
/
books.erl
41 lines (34 loc) · 902 Bytes
/
books.erl
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
-module(books).
-compile(export_all).
-include_lib("stdlib/include/qlc.hrl").
-include_lib("eunit/include/eunit.hrl").
-record(book, {isbn, author, title}).
init() ->
mnesia:create_schema([node()]),
mnesia:start(),
mnesia:create_table(book, [
{attributes, record_info(fields, book)},
{ram_copies, [node()] }
]).
insert(Book) ->
mnesia:transaction(fun() ->
mnesia:write(Book)
end).
high_isbn(#book{ isbn=Isbn}) ->
(Isbn > 60000000) and
(length(integer_to_list(Isbn)) == 8).
select_author_by_title(Title) ->
{atomic, Results} = mnesia:transaction(fun() ->
qlc:eval(qlc:q(
[
X#book.author ||
X <- mnesia:table(book),
Title == X#book.title,
high_isbn(X)]
))
end),
Results.
in_and_out_test() ->
init(),
insert(#book{ isbn=65786970, author="Joe", title="Girlang" }),
["Joe"] = select_author_by_title("Girlang").